Oxidation and reduction of diazofluorene. A pulse-radiolysis study

Packer, John E.; Willson, R. L.

doi:10.1039/p29840001415

Cited by 12 publications

(2 citation statements)

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“…8a In order to account for the by-products; fluorenone and 9-fluorenol, the oxygen centred radical produced in the initiation step would have to be trapped irreversibly by diazofluorene generating molecular nitrogen and 9-hydroxyfluorenyl radicals some of which might be expected to undergo disproportionation; N-protonation of diazofluorene anion radical would generate 9-diazenylfluorenyl radical, disproportionation of which would produce a molecule of fluorenone hydrazone and regenerate one of diazofluorene, as suggested in pulse radiolysis studies. 17 The addition of fluorene to reaction mixtures containing potassium t-butoxide accelerates the conversion of diazofluorene into fluorenone azine and this is consistent with the simple formulation if initiation of the chains is mediated by fluorenyl anions. Electron transfer from the carbanion would afford 9-fluorenyl radicals, leading to the corresponding radical dimer, 9,9Ј-bifluorenyl, as is indeed observed, and to the 1/2-order kinetic dependence on the fluorene concentration.…”

Section: Discussionsupporting

confidence: 69%

The decomposition of diazo-compounds induced by nucleophiles. The decomposition of 9-diazofluorene in the presence of hydroxide or alkoxide ions

2003

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9-Diazofluorene, on treatment with stoichiometric or substoichiometric amounts of quaternary ammonium hydroxide or methoxide or of potassium t-butoxide in solution in aqueous or alcoholic dimethyl sulfoxide or acetonitrile at 30 degrees C, decomposes with evolution of nitrogen to yield fluorenone azine [bis(fluorenylidene)hydrazine] in almost quantitative yield. Studies are reported of the identity of the minor by-products, together with an examination of the kinetics of the reactions and additional spectroscopic experiments. The general rate equation is v = k[FIN2]3/2[Nu-]1/2, where Nu- represents the nucleophile. It is concluded that the oxyanions, most probably after nucleophilic attack on 9-diazofluorene under these basic conditions to generate a new anionic species, are capable of transferring an electron to the diazo-compound. This initiates decomposition of further diazo-molecules in a process of electron-transfer chain catalysis that bears some similarities to, but has also some differences from, that encountered using cathodic initiation. In support of this interpretation it is found that reactions can be accelerated by the introduction of carbon acids (fluorene, 9-phenylfluorene) into the reaction mixtures. The nature of the initiation, propagation and termination steps of the chain mechanism are discussed.

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